Polycrystalline silicon

About: Polycrystalline silicon is a research topic. Over the lifetime, 19554 publications have been published within this topic receiving 198222 citations. The topic is also known as: polysilicon & poly-Si.

Semiconductor substrate having a gettering layer

Abstract: A silicon wafer having a low concentration of oxygen and a silicon wafer having a high concentration of oxygen are joined and polished to prescribed thicknesses to form a semiconductor substrate according to the present invention. A region formed of the wafer having a low concentration of oxygen is used as a region where an element is formed, and a region formed of the wafer having a high concentration of oxygen produces a gettering effect on metal impurities and defects. As a DZ layer having a low concentration of oxygen, a wafer manufactured by an MCZ method or a wafer manufactured by a CZ method is used after being heat-treated at high temperature to diffuse oxygen outward. In another example, a damage layer, a polycrystalline silicon layer, an amorphous silicon layer or the like is formed between a DZ layer and an IG layer.

Laser annealing apparatus, TFT device and annealing method of the same

Abstract: A laser beam is concentrated using an objective lens and radiated on a amorphous silicon film or polycrystalline silicon film having a grain size of one micron or less, the laser beam being processed from a continuous wave laser beam (1) to be pulsed using an EO modulator and to have arbitrary temporal energy change while pulsing ; (2) to have an arbitrary spatial energy distribution using a beam-homogenizer, filter having an arbitrary transmittance distribution, and rectangular slit; and (3) to eliminate coherency thereof using a high-speed rotating diffuser. In this manner, it is possible to realize a liquid crystal display device in which a driving circuit comprising a polycrystalline silicon film having substantially the same properties as a single crystal is incorporated in a TFT panel device.

Representative volume element of polycrystalline silicon for MEMS

Abstract: A nanoscale mechanical deformation measurement method was employed to obtain the Young’s modulus and Poisson’s ratio of polycrystalline silicon for Microelectromechanical Systems (MEMS) from different facilities, and to assess the scale at which these effective properties are valid in MEMS design. The method, based on in situ Atomic Force Microscope (AFM) imaging and Digital Image Correlation (DIC) analysis, employed 2–2.5 μm thick freestanding specimens with surface measurement areas varying between 1×2 and 5×15 μm2. The effective mechanical properties were quite invariant with respect to the fabrication facility: the Poisson’s ratio of polycrystalline silicon from the Multi-user MEMS Processes (MUMPs) and from Sandia’s Ultra planar four layer Multilevel MEMS Technology (SUMMiT-IV) was 0.22±0.02, while the elastic moduli for MUMPs and SUMMiT-IV polysilicon were 164±7 and 155±6 GPa, respectively. The AFM/DIC method was used to determine the size of the material domain whose mechanical behavior could be described by the isotropic constants. For SUMMiT polysilicon with columnar grains and 650 nm average grain size, it was found that a 10×10-μm2 specimen area, on average containing 15×15 columnar grains, was a representative volume element. However, the axial displacement fields in 4×4 or 2×2 μm2 areas could be highly inhomogeneous and the effective behavior of these specimen domains could deviate significantly from that described by isotropy. As a consequence, the isotropic material constants are applicable to MEMS components comprised of 15×15 or more grains, corresponding to specimen areas equal to 10×10 μm2 for SUMMiT and 5×5 μm2 for MUMPs, and do not provide an accurate description of the mechanics of smaller MEMS components.

A bistable snapping microactuator

Abstract: A mechanical bistable switching device, actuated by the interactive forces of a buckling cantilever and a tension band connected to its end, is described. The device has been built using a combination of surface- and bulk-micromachining on materials familiar in IC fabrication: a silicon substrate, LPCVD layers of polycrystalline silicon (polysilicon), silicon nitride, and silicon dioxide. The switching element is a cantilever formed from three thin-film layers: polysilicon, silicon dioxide, and polysilicon. The cantilever is made to buckle as a result of strong axial force from a built-in tension band. Joule heating in one of the two polysilicon layers of the buckled cantilever gives rise to a snapping action that moves the cantilever end /spl plusmn/6 /spl mu/m in a direction perpendicular to the underlying silicon substrate. The overall device length, excluding contact pads, is less than 200 /spl mu/m; it has an 82 /spl mu/m-long buckling cantilever, a 70 /spl mu/m-long silicon nitride tension band, and a 105 /spl mu/m-long extra cantilever, called a tension-band anchor The substrate under the device is recessed to accommodate large vertical movement of the actuator. The device is operated by heating the cantilever asymmetrically with a current of 7 mA at 24 V for 12 /spl mu/sec, after uniform heating of the tension-band anchor with another current pulse of 3 mA at 7.5 V for 50 msec. The fabrication process used to make the device is briefly reported.

Evaluation and Validation of Equivalent Circuit Photovoltaic Solar Cell Performance Models

Abstract: The "five-parameter model" is a performance model for photovoltaic solar cells that predicts the voltage and current output by representing the cells as an equivalent electrical circuit with radiation and temperature-dependent components. An important feature of the five-parameter model is that its parameters can be determined using data commonly provided by module manufacturers on their published datasheets. This paper documents the predictive capability of the five-parameter model and proposes modifications to improve its performance using approximately 30 days of field-measured meteorological and module data from a wide range of cell technologies, including monocrystalline, polycrystalline, amorphous silicon, and copper indium diselenide (CIS). The standard five-parameter model is capable of predicting the performance of monocrystalline and polycrystalline silicon modules within approximately 6% RMS but is slightly less accurate for a thin-film CIS and an amorphous silicon array. Errors for the amorphous technology are reduced to approximately 5% RMS by using input data obtained after the module underwent an initial degradation in output due to aging. The robustness and possible improvements to the five-parameter model were also evaluated. A sensitivity analysis of the five-parameter model shows that all model inputs that are difficult to determine and not provided by manufacturer datasheets such as the glazing material properties, the semiconductor band gap energy, and the ground reflectance may be represented by approximate values independent of the PV technology. Modifications to the five-parameter model tested during this research did not appreciably improve the overall model performance. Additional dependence introduced by a seven-parameter model had a less than 1% RMS effect on maximum power predictions for the amorphous technology and increased the modeling errors for this array 4% RMS at open-circuit conditions. Adding a current sink to the equivalent circuit to better model recombination currents had little effect on the model behavior.